This invention relates to a low forward voltage drop transient voltage suppressor and method of fabricating.
Schottky rectifiers generally have a special barrier metal contact within the device to provide a low forward voltage drop and are widely used in electrical circuits to conduct forward current without significant conduction power loss. However, because the character of metal barrier and barrier lowering under high surface electrical field, Schottky rectifiers have long been denounced for their high reverse leakage at rated reverse voltage as being serious barrier lowering devices having strong surface electrical fields, especially for low barrier height and low reverse voltage Schottky devices. On the other hand, PN structure diodes normally have lower reverse leakage performance than Schottky's. It is therefore unavoidable for the disadvantage of high forward voltage drop even under low current density due to the nature of build-in potential in the PN junction in the device. The application of rectifiers then becomes a trade-off decision for a circuit designer limited by forward conduction loss or reverse power loss.
As a result, in applications such as hard disk control circuit design, for example, relative-high voltage rated Schottky rectifiers and relative-low reverse voltage rated transient voltage suppressors (TVS) are connected in parallel to provide low forward voltage drop (polarity protection) and protect the reverse surge at the two ends in the same time. The existence of the Schottky device is mainly used for polarity protection, to confirm the connection of the two ends in the right direction through its lower forward voltage drop. However, construction costs of this type of circuit are high due to two actual devices, namely the Schottky rectifier and the reverse voltage rated TVS (Transient Voltage Suppressor), which are needed in a control circuit. Thus, it is desirable to have an improvement in the art to reduce the cost of this type of device.
In view of the foregoing, it is a primary object, feature or advantage of the present invention to improve over the state of the art.
It is another object, feature or advantage of the present invention to provide a low forward voltage drop transient voltage suppressor and method of fabricating.
Another object, feature or advantage of the present invention is a low reverse leakage device and method for low reverse breakdown voltage rated Schottky rectifiers.
Another object, feature or advantage of the present invention is to provide a low barrier height and low reverse leakage device and method for Schottky rectifiers.
Another object, feature or advantage of the present invention is to provide a high current rated Schottky rectifier.
Another object, feature or advantage of the present invention is to provide a low forward voltage drop transient voltage suppressor and method of fabricating which takes advantage of unipolar diodes to reduce the forward voltage gap of bi-polar diodes.
Another object, feature or advantage of the present invention is a provision of a low forward voltage drop transient voltage suppressor which is economical to manufacture, durable in use, and efficient in operation.
A further object, feature or advantage of the present invention is to provide a method of fabricating an improved low forward voltage drop transient voltage suppressor.
One or more of these and/or other features or advantages of the present invention will be apparent from the specification and claims that follow. It is to be understood that no single embodiment need exhibit all or any of these objects, features or advantages.